Radial tire having breaker structure

ABSTRACT

The invention relates to improvements in the breaker structure for radial type pneumatic tires. The structure according to the invention comprises at least two superposed strips of textile material having at least one strip of metallic material interposed therebetween and an additional metallic or equivalent strip arranged radially outermost of the aforementioned strips. The improvement in the present invention resides in the fact that at least one of the textile strips is folded so as to provide a fold line along each edge of the structure.

United States Patent Barassi et al.

[ Sept. 12, 1972 RADIAL TIRE HAVING BREAKER STRUCTURE Inventors: CarloBarassi; Giuseppe Lugli;

Mario Mezzanotte; Romano Guermandi, all of Milan, Italy Assignee:Industrie Pirelli S.p.A., Milan, Italy Filed: April 30, 1971 Appl. No.:138,895

Foreign Application Priority Data May 5, 1970 Italy ..24l74 A/70 US. Cl..152/361 Int. Cl. ..B60c 9/18 Field of Search ..l52/36l [56] ReferencesCited FOREIGN PATENTS OR APPLICATIONS 862,522 2/1971 Canada ..l52/36lPrimary Examiner-Gerald M. Forlenza Assistant ExaminerGeorge H. LibmanAttorney-Stevens, Davis, Miller & Mosher 7] ABSTRACT 8 Claims, 4 DrawingFigures PATENTED I973 3.690.364

ll 0c J L -4 1x F IG. 2 (x INVENTORS CARLO BARASSI SEPPE LUGLI MA MANOTTE RQMANO RMANDI ATTORNEYS PATENTEUSEP 12 m2 3.690.364

SHEET 2 OF 2 INVE RS CA BARAS GIU PE LUGLI MARIO MEZ OTTE ROMANO GU AND!ATTORNEYS RADIAL TIRE HAVING BREAKER STRUCTURE This application relatesto improvements relative to the invention disclosed in US. Pat.application Ser. No. 73,112 filedSept. 17,1970.

The aforementioned application concerns radiaP tires, namely tiresprovided with a carcass'formed by cords lying in radial planes orforming small angles with said planes; more precisely it relates to thebreaker structures of radial tires, namely to those relatively stiffannular structures which are inserted between the tread and the carcass.According according to the prior application, the breaker structurecomprises the following elements:

a. at least two superimposed strips of textile material,

whose cords are inclined, with respect to the midcircumferential plane,at an angle ranging between and 30;

; at least a strip made of metal, or of another material having a highmodulus of elasticity, inserted between said textile strips, thecords ofsaid metal strip being inclined in opposite direction at an angleranging between 13 and 33, and said angle being greater by at least 2than the angle formed by the cords of the textile strips;

0. an additional strip of metallic material or of anothercompression-resistant material, arranged in radially outer position andhaving its cords inclined at an angle ranging between 60 and 90 withrespect to the mid-circumferential plane.

A breaker structure having this configuration is particularly suitablefor tires intended to be used on very fast cars, since it confers tosuch tires high characteristics of road holding and driving safety,without anyhow affecting their comfort.

Moreover, the presence of the metallic additional strip, arranged inradially outer positions, constitutes a solid support for the treadblocks, which are therefore stiffer and less flexible when they are incontact with the ground.

This tendency of the blocks to remain in their original molding positioncontributes in a relevant manner to eliminate their creeping on theground, and therefore to reduce localized irregular wear of the tread;moreover, it improves considerably the road holding of the tire on wetground, since water discharge from the grooves of the tread isfacilitated.

The present additional application aims at specifying furtherembodiments of the object of said prior application, by means of which,besides ensuring the above advantages, considerable improvements areobtained as regards tire life.

These embodiments are therefore particularly suitable in those cases inwhich the main problem is a long tire mileage.

The object of the present application is accordingly a pneumatic tirefor vehicle wheels, which comprises a radial carcass and a breakerstructure formed by strips of cord fabric of textile material and bystrips of cord fabric of metallic material or of anothercompressionresistant material, the cords of such strips being inclinedwith respect to the mid-circumferential plane, said breaker structurecomprising at least two superimposed strips of textile material whosecords are inclined at an angle ranging between 10 and in one directionwith respect to the mid-circumferential plane,

at least one strip of metallic material or of another material having ahigh modulus of elasticity, inserted between said textile trips, whosecords are inclined in an opposite direction at an angle ranging between13 and 33, said angle being greater by at least 2 than the angle formedby the cords of said textile strips, an additional strip of metallicmaterial or of another compression-resistant material arranged in aradiallyv outer position, whose-cords form with the mid-circumferentialplane an angle ranging between 60 and 90, the foregoing being inaccordance with said prior application and the improvement being in thatat least one of the strips of textile material is folded in such a waythat at least one folding line is present at each of the lateral edgesof the breaker structure.

In the present application the width of the breaker structure is definedby thedistance between the folding lines of the strips, said foldinglines constituting therefore the lateral edges of the breaker, saidwidth, in the tires according to the invention, being substantiallyequal to that existing in the convention breakers of radial tires.

As in the prior application, the expression textile material has themeaning conventionally attributed to it in the tire industry andcomprises, by way. of example, organic textile materials, as cotton andrayon; fibers from synthetic polymers, as polyamide fibers, polyesterfibers and so on.

The advantage of having folding lines at the lateral edges of thebreaker structure is due to the fact that said'zones are considerablystiffened, so thatit is possible to reduce the width of the additionalstrip of metallic material, arranged in radially outermost position,without anyhow reducing the rigidity of the base of the tread blocks,which rigidity is essential to reduce the creeping of the tire on theground and to improve its road holding on wet ground, as describedabove.

In a preferred embodiment, of the present invention, one of the stripsof textile material, preferably that situated in a radially outermostposition with respect to the other textile strip, is provided with twofoldings, one at each lateral edge of the breaker; the other textilestrip is not provided with foldings.

Preferably, one of the folded skirting is directed radially inwardly,and the other radially outwardly.

According to a further embodiment, one textile strip is folded at oneedge of the breaker, whilst the other textile strip is folded at theedge opposite to it.

In both cases, the folded textile strips have at least two skirtings ofdifferent width; the smaller skirting has a width ranging between 20 and40 percent of the total width of the breaker, whilst the larger skirtinghas such a width that, whichever is the arrangement of the textilestrips, its value does never exceed the width of the breaker as definedabove.

Moreover, in both embodiments, the additional strip of metallicmaterial, arranged in a radially outer position, has preferably a width,ranging between and percent of the width-of the breaker as definedabove.

It has been surprisingly ascertained that, by limiting the width of theadditional strip to the above indicated range of values, the life of thewhole structure of the tire is considerably increased.

Probably, this is due to a better distribution of the bending stressesof the breaker structure in its area of contact with the ground.

According to a further preferred embodiment, the strip of metallicmaterial interposed between the textile strips has a width rangingbetween 100 and 120 percent with respect to the width of the breaker.

The present invention will now be better described with reference to theattached drawings, given by way of example, in which:

FIGS. 1 and 3 represent diagrammatically the section of two tiresaccording the present invention;

FIGS. 2 and 4 represent in plan view the breaker structures of the tiresshown in FIGS. 1 and 3, respectively, with parts broken away toillustrate the path of the cords.

FIGS. 1 and 2 represent an embodiment of the present invention; the tireaccording to this embodiment comprises a tread 1 and a carcass 2, formedby cords lying in radial planes.

A breaker structure 3, comprising two strips 4 and 5 of textilematerial, more precisely rayon, is inserted between the tread and thecarcass; strip 4 is not folded, whilst strip 5 is folded in such a wayas to show two foldings 6 and 7.s ubstantially lying at each lateraledge of the breaker, in order to originate two lateral skirtings 8 and9.

Whilst skirting 8 is radially turned towards the tire inside, theopposite skirting 9 is turned towards the tread.

The width of the central skirting 10 of strip 5 is substantially equalto the width commonly adopted in the breakers of radial tires; thefolded skirtings 8 and 9 have a .width equal to 30 percent of that ofskirting 10. The width of strip 4 does not substantially differ fromthat of skirting 10, except for the amount necessary to obtain a normalgraduality between the lateral edges of the two textile strips.

The cords of strip 4 and of the central skirting 10 of strip 5 aredirected in the same sense and form an angle a of 18 with respect to themid-circumferential plane of the tire.

A strip 11, formed by metal cords parallel to one another and inclinedat an angle ,8 of 22 with respect to the mid-circumferential plane ofthe tire, is interposed between strips 4 and 5.

The inclination of said meal cords is directed in a sense opposite tothat of the textile cords of strip 4.

Strip 11 has a width equal to 110 percent of the width of the centralskirting 10 of strip 5.

An additional strip 12, formed by metal cords parallel to one anotherand inclined at an angle 7 of 80 with respect to the mid-circumferentialplane of the tire, is disposed on strips 4, 5 and 11.

The inclination of these metal cords is directed in a sense opposite tothat of the textile cords of the larger skirting 10 of the textile strip5.

The width of the additional strip 12 is equal to 80 percent of the widthof the larger skirting 10 of the textile strip 5.

FIGS. 3 and 4 represent a further embodiment of the invention, accordingto which the breaker 13, interposed between the tread 14 and the carcass15, comprises two strips 16 and 17 of textile material.

Strip 16 is folded along the folding line 18, lying at one of thelateral edges of the breaker, so as to form a central skirting having awidth slightly smaller than the breaker width and a second lateralskirting 19 having a width equal to 30 percent of the breaker width.

Likewise, strip 17 is folded along the folding line 20, at the otherlateral edge of the breaker, so as to form a central skirting having awidth slightly smaller than the breaker width, and a second lateralskirting 21 having a width equal to 30 percent of the breaker width.

Both skirtings 19 and 21 are radially turned up towards the tread.

The skirtings of larger width of strips 16 and 17 have their textilecords inclined in the same direction, at an angle a of 18 with respectto the mid-circumferential plane of the tire.

A strip 22, formed by metal cords parallel to one another and inclinedat an angle [3' of 22 with respect to the mid-circumferential plane, isinterposed between strips 16 and 17.

The inclination of such metal cords has a direction opposite to those ofthe textile cords of the larger skirtings of strips 16 and 17.

The strip 22 has a width greater than the distance between the twofolding lines 18 and 20 of strips 16 and 17, which distance defines thewidth of the breaker, and the width of said strip is equal to 1 10percent of the breaker width.

An additional strip 23, formed by metal cords parallel to one anotherand inclined at an angle 7 of with respect to the mid-circumferentialplane of the tire, is arranged on strips l6, l7 and 21.

The inclination of these metal cords has a direction opposite to that ofthe textile cords of the larger skirting of the underlying strip 17.

The width of the additional strip 23 is equal to 80 percent of thebreaker width.

It is understood that the present invention is not limited to the abovereported examples, but that it includes any other alternativeembodiments deriving from the above indicated inventive principle.

What is claimed is:

1. A pneumatic tire for vehicle wheels, which comprises a radial carcassand a breaker structure formed by strips of cord fabric of textilematerial and by strips of cord fabric of metallic material or of anothercompression-resistant material, the cords of such strips being inclinedwith respect to the mid-circumferential plane, said breaker structurecomprisingat least two superimposed strips of textile material whosecords are inclined at an angle ranging between 10 and 30 in onedirection with respect to the mid-circumferential plane, at least onestrip of metallic material or of another material having a high modulusof elasticity, inserted between said textile strips, whose cords areinclined in an opposite direction at an angle ranging between 13 and 33,said angle being greater by at least 2 than the angle formed by thecords of said textile strips, an additional strip of metallic materialor of another compression-resistant material arranged in a radiallyouter position, whose cords form with he mid-circumferential plane anangle ranging between 60 and characterized in that at least one of thestrips of textiles material is folded in such a way that at least onefolding line is present at each of the lateral edges of the breakerstructure.

2. A pneumatic tire as in claim 1, characterized in that one of thestrips of textile material has a folding at each lateral edge of thebreaker, whilst the other strip of textile material is not folded.

3. A pneumatic tire as in claim 2, characterized in that the foldedtextile strip is arranged in a radially outermost position with respectto the other textile strip.

4. A pneumatic tire as in claim 2, characterized in that one of thefolded skirtings is directed radially inwardly whilst the other isdirected radially outwardly.

5. A pneumatic tire as in claim 1, characterized in that one textilestrip is folded at one edge of the breaker, whilst the other textilestrip is folded at the opposite edge.

6. A pneumatic tire as in claim 1, characterized in that the foldedtextile strips have at least two skirtings of different width, thesmaller skirting having a width ranging between 20 and 40 percent withrespect to the breaker width, and the larger skirting having a widthsuch that, whichever is the arrangement of the textile strips, its valueis never higher than the breaker width.

7 A pneumatic tire as in claim 1, characterized in that the additionalstrip of metallic material, arranged in radially outer position, has awidth ranging between and percent with respect to the breaker width.

8. A pneumatic tire as in claim 1 characterized in that the strip ofmetallic material interposed between the textile strips has a widthranging between and percent with respect to the breaker width.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 36Dated September 12, 1972 lnventofls) Carlo BARASSI et al It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Please correct the following errors:

Column 1, line 12, cancel "according" (second occurrence);

line 38, change "positions" to position,- Column 2, line 3, change"trips" to strips;

line 22, change "convention" to -conventional-; line 39, cancel thecomma after "embodiment"; Column 4, line 58 change "he" to -the-;

line 60,- change "textiles" to -textile-.

Signed and sealed this 6th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT SOTTSCHALK Attesting Officer Commissionerof Patents FORM P0405" (1069) USCOMM-DC 0O376-P69 "h U.S. COVIRNNINYPRINYING OFFICE: I969 O-J66-3J4

1. A pneumatic tire for vehicle wheels, which comprises a radial carcassand a breaker structure formed by strips of cord fabric of textilematerial and by strips of cord fabric of metallic material or of anothercompression-resistant material, the cords of such strips being inclinedwith respect to the midcircumferential plane, said breaker structurecomprising at least two superimposed strips of textile material whosecords are inclined at an angle ranging between 10* and 30* in onedirection with respect to the mid-circumferential plane, at least onestrip of metallic material or of another material having a high modulusof elasticity, inserted between said textile strips, whose cords areinclined in an opposite direction at an angle ranging between 13* and33*, said angle being greater by at least 2* than the angle formed bythe cords of said textile strips, an additional strip of metallicmaterial or of another compression-resistant material arranged in aradially outer position, whose cords form with he mid-circumferentialplane an angle ranging between 60* and 90*, characterized in that atleast one of the strips of textiles material is folded in such a waythat at least one folding line is present at each of the lateral edgesof the breaker structure.
 2. A pneumatic tire as in claim 1,characterized in that one of the strips of textile material has afolding at each lateral edge of the breaker, whilst the other strip oftextile material is not folded.
 3. A pneumatic tire as in claim 2,characterized in that the folded textile strip is arranged in a radiallyoutermost position with respect to the other textile strip.
 4. Apneumatic tire as in claim 2, characterized in that one of the foldedskirtings is directed radially inwardly whilst the other is directedradially outwardly.
 5. A pneumatic tire as in claim 1, characterized inthat one textile strip is folded at one edge of the breaker, whilst theother textile strip is folded at the opposite edge.
 6. A pneumatic tireas in claim 1, characterized in that the folded textile strips have atleast two skirtings of different width, the smaller skirting having awidth ranging between 20 and 40 percent with respect to the breakerwidth, and the larger skirting having a width such that, whichever isthe arrangement of the textile strips, its value is never higher thanthe breaker width.
 7. A pneumatic tire as in claim 1, characterized inthat the additional strip of metallic material, arranged in radiallyouter position, has a width ranging between 70 and 90 percent withrespect to the breaker width.
 8. A pneumatic tire as in claim 1characterized in that the strip of metallic material interposed betweenthe textile strips has a width ranging between 100 and 120 percent withrespect to the breaker width.